The difference between entering W-2 income and self-employment income is that if you have a W-2, an employer has withheld federal and state tax, and Social Security and Medicare. When you are self-employed, you pay all of that yourself at tax time or during the year by paying estimated quarterly tax payments.
You do not have a "choice" of which kind of income to enter. You enter what you received--whether you got a W-2 from an employer or a 1099Misc for self-employment--or even if you received cash as an independent contractor.
https://ttlc.intuit.com/questions/2584365-am-i-an-employee-or-an-independent-contractor
https://ttlc.intuit.com/questions/2903027-how-do-i-report-income-from-self-employment
https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922
https://ttlc.intuit.com/questions/2902389-why-am-i-paying-self-employment-tax
https://ttlc.intuit.com/questions/2893577-does-a-1099-misc-mean-i-m-self-employed